Although 90% of clinical cases of American
visceral leishmaniasis (AVL) occur in the northeastern
region of Brazil, the incidence of cases in recent years
has increased in southeastern states such as Minas Gerais
(MG), where the disease has been reported in several
cities, including Belo Horizonte, the state capital. Some
studies have shown a strong correlation between the
incidence of AVL and canine visceral leishmaniasis
(CVL) in Belo Horizonte. A study of 108 dogs with
parasite Leishmania chagasi detected by immunohistochemistry
in healthy ear skin was obtained from
two distinct geographical areas: 55 from a metropolitan
area of the municipality (Santa Luzia, MG) and 53 dogs
from a central area of Belo Horizonte. In parallel, a
group of 10 beagles were experimentally infected with
L. chagasi. Considering the clinical aspects of all
naturally infected dogs, symptomatic dogs were more
frequent than asymptomatic ones, especially animals
from the metropolitan area compared with the central
area (79.6% and 20.3%, respectively). A chronic exudate
was observed in the ear of 51 out of 55 dogs naturally
infected from the metropolitan area (92.7%) and 45 out
of 53 dogs naturally infected from the central area
(84.9%). Importantly, asymptomatic dogs from the
central area harbor more parasites in the skin than the
asymptomatic ones from the metropolitan area. In
addition, a profound difference was noted in the intensity
of the inflammatory reaction and parasite load in the
skin of experimental infected dogs.